As a part of a continuing series on the delayed effects of ionizing irradiation on the brain of the monkey, the current effort sequential observations after whole brain exposure to 6000 rads of super-voltage radiation, in divided doses over a six-week period. The protocol simulates as closely as possible that used by twelve medical centers in therapy of malignant gliomas in humans. The current phase is primarily concerned with converting the assembled data to manuscript form for publication in scientific journals.